h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

This entry is seriously out of date. It says that the only way you can catch an e-mail virus is by receiving and opening an attachment. It says the e-mail message itself is plain ascii text and is never executed so it can not contain a virus.

This is not true. It is possible to send e-mail messages which contain a type of macro language. This will normally be executed by Microsoft Outlook as soon as the e-mail itself (not any attachment) is opened. It is therefore possible to catch a virus just by opening an e-mail, if your e-mail program is Outlook and it is set up using the default settings.

This is very true. Vulnerabilities within e-mail, web browser and other software on your PC mean that the computer can be fooled into thinking that data (such as text in an e-mail) should be executed as a program.

It is also worth noting that e-mail is not the only method by which viruses are spread. Recent (as of September 2003) MS Blaster and Nachi viruses can be caught simply by connecting to the Internet.

There are many other theoretical vulnerabilities yet to be exploited by viruses. Where the next one comes from is anyone's guess.